Overlapping courses of shingles are often applied to the sloped roofs of buildings to protect the roof against the elements. The installation of these shingles typically is a manual process involving several workmen who transport, position and then fasten each shingle to the roof by hand with nails or similar fasteners. A series of chalk line markings often are used as part of this manual procedure in order to align the shingles properly with respect to the edge of the roof and achieve the desired overlap of the successive courses of shingles. For conventional three-in-one residential shingles, this means that a chalk line needs to be provided every five inches or so up the slope of the roof. For these reasons, shingling a roof often constitutes a laborious, tedious, and costly undertaking.
Many machines have been proposed for overcoming the disadvantages of the manual shingling process. Such machines, however, suffer various deficiencies of their own which renders them commercially unviable. For instance, some machines have a motorized carriage to transport and lay the shingles upon the roof. Such machines, however, are costly, heavy and cumbersome making them difficult to handle and operate by one person.
There are other systems employing nonmotorized carriages and complicated, cumbersome tracking systems which guide the carriages along the roof. These systems also are difficult for a single workman to use effectively and are not known to be widely used commercially.